Ecg belt systems to interoperate with imds

ABSTRACT

An electrode apparatus includes a portable amplifier and a plurality of external electrodes to be disposed proximate a patient&#39;s skin. A portable computing apparatus is operably coupled to the electrode apparatus. The portable computing apparatus is configured to monitor electrical activity from tissue of a patient using the plurality of external electrodes to generate a plurality of electrical signals over time. The portable computing apparatus is configured to perform at least one of optimizing at least one parameter of the of the implantable pacing device based on the plurality of electrical signals and determining cardiac synchrony based on the plurality of electrical signals.

This application claims the benefit under 35 U.S.C. § 119 of U.S.Provisional Application No. 63/058,943, filed Jul. 30, 2020, which isincorporated herein by reference in its entirety.

The disclosure herein relates to systems and methods for a portablediagnostic system using a plurality of external electrodes.

Implantable medical devices (IMDs), such as implantable pacemakers,cardioverters, defibrillators, or pacemaker-cardioverter-defibrillators,provide therapeutic electrical stimulation to the heart. IMDs mayprovide pacing to address bradycardia, or pacing or shocks in order toterminate tachyarrhythmia, such as tachycardia or fibrillation. In somecases, the medical device may sense intrinsic depolarizations of theheart, detect arrhythmia based on the intrinsic depolarizations (orabsence thereof), and control delivery of electrical stimulation to theheart if arrhythmia is detected based on the intrinsic depolarizations.IMDs may also provide cardiac resynchronization therapy (CRT), which isa form of pacing. CRT involves the delivery of pacing to the leftventricle, or both the left and right ventricles. The timing andlocation of the delivery of pacing pulses to the ventricle(s) may beselected to improve the coordination and efficiency of ventricularcontraction.

Systems for implanting medical devices may include workstations or otherequipment in addition to the implantable medical device itself. In somecases, these other pieces of equipment assist the physician or othertechnician with placing the intracardiac leads at particular locationson the heart. In some cases, the equipment provides information to thephysician about the electrical activity of the heart and the location ofthe intracardiac lead. The equipment may perform similar functions asthe medical device, including delivering electrical stimulation to theheart and sensing the depolarizations of the heart. In some cases, theequipment may include equipment for obtaining an electrocardiogram (ECG)via electrodes on the surface, or skin, of the patient. Morespecifically, the patient may have a plurality of electrodes on an ECGbelt or vest that surrounds the torso of the patient. After the belt orvest has been secured to the torso, a physician can perform a series oftests to evaluate a patient's cardiac response. The evaluation processcan include detection of a baseline rhythm in which no electricalstimuli is delivered to cardiac tissue and another rhythm afterelectrical stimuli is delivered to the cardiac tissue.

The ECG electrodes placed on the body surface of the patient may be usedfor various therapeutic purposes (e.g., cardiac resynchronizationtherapy) including optimizing lead location, pacing parameters, etc.based on one or more metrics derived from the signals captured by theECG electrodes. For example, electrical heterogeneity information may bederived from electrical activation times computed from multipleelectrodes on the body surface.

SUMMARY

The exemplary systems and methods described herein may be configured toassist users (e.g., physicians and/or nurses) in configuring cardiactherapy (e.g., cardiac therapy being performed on a patient duringand/or after implantation of cardiac therapy apparatus). According tovarious configurations, the systems and methods herein are configured tobe performed in an at least partially autonomous or a fully autonomousmanner such that a user (e.g., a physician and/or a patient) may not beinvolved in the process. The systems and methods may be described asbeing noninvasive. For example, the systems and methods may not needimplantable devices such as leads, probes, sensors, catheters, etc. toevaluate and configure the cardiac therapy. Instead, the systems andmethods may use electrical measurements taken noninvasively using, e.g.,a plurality of external electrodes attached to the skin of a patientabout the patient's torso.

One exemplary system for use in cardiac evaluation may include anelectrode apparatus comprising a portable amplifier and a plurality ofexternal electrodes to be disposed proximate a patient's skin. Aportable computing apparatus is operably coupled to the electrodeapparatus. The portable computing apparatus is configured to monitorelectrical activity from tissue of a patient using the plurality ofexternal electrodes to generate a plurality of electrical signals overtime. The portable computing apparatus is configured to perform at leastone of optimizing at least one parameter of the of the implantablepacing device based on the plurality of electrical signals anddetermining cardiac synchrony based on the plurality of electricalsignals.

One exemplary method for use in cardiac evaluation may includemonitoring electrical activity from tissue of a patient using aplurality of external electrodes to generate a plurality of electricalsignals over time. A portable computing apparatus is operably coupled tothe plurality of electrodes. The portable computing apparatus isconfigured to perform at least one of optimizing at least one parameterof the of the implantable pacing device based on the plurality ofelectrical signals and determining cardiac synchrony based on theplurality of electrical signals.

One exemplary system for use in cardiac evaluation comprises anelectrode apparatus comprising a portable amplifier and a plurality ofexternal electrodes to be disposed proximate a patient's skin. Aportable computing apparatus comprising processing circuitry, thecomputing apparatus is operably coupled to the electrode apparatus andis configured to be operably coupled to an implantable pacing device ofthe patient. The portable computing apparatus is configured to monitorelectrical activity from tissue of a patient using the plurality ofexternal electrodes to generate a plurality of electrical signals overtime. One or more parameters of the patient are measured based on theplurality of electrical signals. One or more metrics of the patient aredetermined based on the one or more parameters. The one or more metricsare transmitted to a smart device. According to various embodiments, theone or more transmitted metrics are used to configure the implantabledevice to another configuration.

One exemplary method for use in cardiac evaluation comprises monitoringelectrical activity from tissue of a patient using a plurality ofexternal electrodes to generate a plurality of electrical signals overtime. Using a portable computing apparatus operably coupled to theplurality of electrodes, one or more parameters of the patient aremeasured based on the plurality of electrical signals. One or moremetrics of the patient are determined based on the one or moreparameters. The one or more metrics are transmitted to a smart device.Embodiments described herein comprise an ECG belt and an

amplifier. With a reusable belt integrated with miniaturized smartamplifier system, this could be an external smart portable diagnosticsystem that can be used for in-home monitoring in patients with orwithout implantable cardiac devices. Such a system communicates with atablet, smart phone, smart watch or other smart devices with requisiteamount of security encryption to display diagnostic data on cardiacdyssynchrony and pacing (for patients with implantable cardiac pacingdevices) or can transfer device and ECG and electrical dyssynchrony datathrough a secure medical medium. In some cases, the system describedherein may be used in a clinical setting and/or for hospital monitoring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an exemplary system including electrodeapparatus, display apparatus, and computing apparatus.

FIGS. 2-3 are diagrams of exemplary external electrode apparatus formeasuring torso-surface potentials.

FIGS. 4A-4C show exemplary systems having an ECG belt and a portableamplifier.

FIG. 5 shows an exemplary method for optimizing pacing parameters.

FIG. 6 illustrates another exemplary method for optimizing pacingparameters.

FIG. 7 shows an example of determining if capture has occurred atdifferent pacing outputs.

FIG. 8 shows an exemplary system for collecting cardiac dyssynchronydata using a portable ECG belt and a portable amplifier.

FIG. 9 illustrates an exemplary method for using an ECG belt with aportable amplifier to collect cardiac dyssynchrony data.

FIG. 10 illustrates an example of a QRS complex

FIG. 11 is a diagram of an illustrative system including an illustrativeimplantable medical device (IMD).

FIG. 12A is a diagram of the illustrative IMD of FIG. 11.

FIG. 12B is a diagram of an enlarged view of a distal end of theelectrical lead disposed on the left ventricle of FIG. 12A.

FIG. 13A is a block diagram of an illustrative IMD, e.g., of the systemsof FIGS. 11-12.

FIG. 13B is another block diagram of an illustrative IMD (e.g., animplantable pulse generator) circuitry and associated leads employed inthe systems of FIGS. 11-12).

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the following detailed description of illustrative embodiments,reference is made to the accompanying figures of the drawing which forma part hereof, and in which are shown, by way of illustration, specificembodiments which may be practiced. It is to be understood that otherembodiments may be utilized and structural changes may be made withoutdeparting from (e.g., still falling within) the scope of the disclosurepresented hereby.

Illustrative systems and methods shall be described with reference toFIGS. 1-12. It will be apparent to one skilled in the art that elementsor processes from one embodiment may be used in combination withelements or processes of the other embodiments, and that the possibleembodiments of such systems, methods, and devices using combinations offeatures set forth herein is not limited to the specific embodimentsshown in the Figures and/or described herein. Further, it will berecognized that the embodiments described herein may include manyelements that are not necessarily shown to scale. Still further, it willbe recognized that timing of the processes and the size and shape ofvarious elements herein may be modified but still fall within the scopeof the present disclosure, although certain timings, one or more shapesand/or sizes, or types of elements, may be advantageous over others.

A plurality of electrocardiogram (ECG) signals (e.g., torso-surfacepotentials) may be measured, or monitored, using a plurality of externalelectrodes positioned about the surface, or skin, of a patient. The ECGsignals may be used to evaluate and configure cardiac therapy such as,e.g., cardiac therapy provide by an implantable medical deviceperforming cardiac resynchronization therapy (CRT). As described herein,the ECG signals may be gathered or obtained noninvasively since, e.g.,implantable electrodes may not be used to measure the ECG signals.Further, the ECG signals may be used to determine cardiac electricalactivation times, which may be used to generate various metrics (e.g.,electrical heterogeneity information) that may be used by a user (e.g.,physician) to optimize one or more settings, or parameters, of cardiactherapy (e.g., pacing therapy) such as CRT.

Various illustrative systems, methods, and graphical user interfaces maybe configured to use electrode apparatus including external electrodes,display apparatus, and computing apparatus to noninvasively assist auser (e.g., a physician) in the evaluation of cardiac health and/or theconfiguration (e.g., optimization) of cardiac therapy. An illustrativesystem 100 including electrode apparatus 110, computing apparatus 140,and a remote computing device 160 is depicted in FIG. 1.

The electrode apparatus 110 as shown includes a plurality of electrodesincorporated, or included, within a band wrapped around the chest, ortorso, of a patient 14. The electrode apparatus 110 is operativelycoupled to the computing apparatus 140 (e.g., through one or wiredelectrical connections, wirelessly, etc.) to provide electrical signalsfrom each of the electrodes to the computing apparatus 140 for analysis,evaluation, etc. Illustrative electrode apparatus may be described inU.S. Pat. No. 9,320,446 entitled “Bioelectric Sensor Device and Methods”filed Mar. 27, 2014 and issued on Mar. 26, 2016, which is incorporatedherein by reference in its entirety. Further, illustrative electrodeapparatus 110 will be described in more detail in reference to FIGS.2-3.

Although not described herein, the illustrative system 100 may furtherinclude imaging apparatus. The imaging apparatus may be any type ofimaging apparatus configured to image, or provide images of, at least aportion of the patient in a noninvasive manner. For example, the imagingapparatus may not use any components or parts that may be located withinthe patient to provide images of the patient except noninvasive toolssuch as contrast solution. It is to be understood that the illustrativesystems, methods, and interfaces described herein may further useimaging apparatus to provide noninvasive assistance to a user (e.g., aphysician) to locate, or place, one or more pacing electrodes proximatethe patient's heart in conjunction with the configuration of cardiactherapy.

For example, the illustrative systems and methods may provide imageguided navigation that may be used to navigate leads includingelectrodes, leadless electrodes, wireless electrodes, catheters, etc.,within the patient's body while also providing noninvasive cardiactherapy configuration including determining an effective, or optimal,pre-excitation intervals such as A-V and V-V intervals, etc.Illustrative systems and methods that use imaging apparatus and/orelectrode apparatus may be described in U.S. Pat. App. Pub. No.2014/0371832 to Ghosh published on Dec. 18, 2014, U.S. Pat. App. Pub.No. 2014/0371833 to Ghosh et al. published on Dec. 18, 2014, U.S. Pat.App. Pub. No. 2014/0323892 to Ghosh et al. published on Oct. 30, 2014,U.S. Pat. App. Pub. No. 2014/0323882 to Ghosh et al. published on Oct.20, 2014, each of which is incorporated herein by reference in itsentirety.

Illustrative imaging apparatus may be configured to capture x-ray imagesand/or any other alternative imaging modality. For example, the imagingapparatus may be configured to capture images, or image data, usingisocentric fluoroscopy, bi-plane fluoroscopy, ultrasound, computedtomography (CT), multi-slice computed tomography (MSCT), magneticresonance imaging (MRI), high frequency ultrasound (HIFU), opticalcoherence tomography (OCT), intra-vascular ultrasound (IVUS), twodimensional (2D) ultrasound, three dimensional (3D) ultrasound, fourdimensional (4D) ultrasound, intraoperative CT, intraoperative MRI, etc.Further, it is to be understood that the imaging apparatus may beconfigured to capture a plurality of consecutive images (e.g.,continuously) to provide video frame data. In other words, a pluralityof images taken over time using the imaging apparatus may provide videoframe, or motion picture, data. An exemplary system that employsultrasound can be found in U.S. Pat. App. Pub. No. 2017/0303840 entitledNONINVASIVE ASSESSMENT OF CARDIAC RESYNCHRONIZATION THERAPY to Stadleret al., incorporated by reference in its entirety. Additionally, theimages may also be obtained and displayed in two, three, or fourdimensions. In more advanced forms, four-dimensional surface renderingof the heart or other regions of the body may also be achieved byincorporating heart data or other soft tissue data from a map or frompre-operative image data captured by MRI, CT, or echocardiographymodalities. Image datasets from hybrid modalities, such as positronemission tomography (PET) combined with CT, or single photon emissioncomputer tomography (SPECT) combined with CT, could also providefunctional image data superimposed onto anatomical data, e.g., to beused to navigate implantable apparatus to target locations within theheart or other areas of interest.

Systems and/or imaging apparatus that may be used in conjunction withthe illustrative systems and method described herein are described inU.S. Pat. App. Pub. No. 2005/0008210 to Evron et al. published on Jan.13, 2005, U.S. Pat. App. Pub. No. 2006/0074285 to Zarkh et al. publishedon Apr. 6, 2006, U.S. Pat. No. 8,731,642 to Zarkh et al. issued on May20, 2014, U.S. Pat. No. 8,861,830 to Brada et al. issued on Oct. 14,2014, U.S. Pat. No. 6,980,675 to Evron et al. issued on Dec. 27, 2005,U.S. Pat. No. 7,286,866 to Okerlund et al. issued on Oct. 23, 2007, U.S.Pat. No. 7,308,297 to Reddy et al. issued on Dec. 11, 2011, U.S. Pat.No. 7,308,299 to Burrell et al. issued on Dec. 11, 2011, U.S. Pat. No.7,321,677 to Evron et al. issued on Jan. 22, 2008, U.S. Pat. No.7,346,381 to Okerlund et al. issued on Mar. 18, 2008, U.S. Pat. No.7,454,248 to Burrell et al. issued on Nov. 18, 2008, U.S. Pat. No.7,499,743 to Vass et al. issued on Mar. 3, 2009, U.S. Pat. No. 7,565,190to Okerlund et al. issued on Jul. 21, 2009, U.S. Pat. No. 7,587,074 toZarkh et al. issued on Sep. 8, 2009, U.S. Pat. No. 7,599,730 to Hunteret al. issued on Oct. 6, 2009, U.S. Pat. No. 7,613,500 to Vass et al.issued on Nov. 3, 2009, U.S. Pat. No. 7,742,629 to Zarkh et al. issuedon Jun. 22, 2010, U.S. Pat. No. 7,747,047 to Okerlund et al. issued onJun. 29, 2010, U.S. Pat. No. 7,778,685 to Evron et al. issued on Aug.17, 2010, U.S. Pat. No. 7,778,686 to Vass et al. issued on Aug. 17,2010, U.S. Pat. No. 7,813,785 to Okerlund et al. issued on Oct. 12,2010, U.S. Pat. No. 7,996,063 to Vass et al. issued on Aug. 9, 2011,U.S. Pat. No. 8,060,185 to Hunter et al. issued on Nov. 15, 2011, andU.S. Pat. No. 8,401,616 to Verard et al. issued on Mar. 19, 2013, eachof which is incorporated herein by reference in its entirety.

The computing apparatus 140 and the remote computing device 160 may eachinclude display apparatus 130, 170, respectively, that may be configuredto display and analyze data such as, e.g., electrical signals (e.g.,electrocardiogram data), electrical activation times, electricalheterogeneity information, etc. For example, one cardiac cycle, or oneheartbeat, of a plurality of cardiac cycles, or heartbeats, representedby the electrical signals collected or monitored by the electrodeapparatus 110 may be analyzed and evaluated for one or more metricsincluding activation times and electrical heterogeneity information thatmay be pertinent to the therapeutic nature of one or more parametersrelated to cardiac therapy such as, e.g., pacing parameters, leadlocation, etc. More specifically, for example, the QRS complex of asingle cardiac cycle may be evaluated for one or more metrics such as,e.g., QRS onset, QRS offset, QRS peak, electrical heterogeneityinformation (EHI), electrical activation times referenced to earliestactivation time, left ventricular or thoracic standard deviation ofelectrical activation times (LVED), standard deviation of activationtimes (SDAT), average left ventricular or thoracic surrogate electricalactivation times (LVAT), QRS duration (e.g., interval between QRS onsetto QRS offset), difference between average left surrogate and averageright surrogate activation times, relative or absolute QRS morphology,difference between a higher percentile and a lower percentile ofactivation times (higher percentile may be 90%, 80%, 75%, 70%, etc. andlower percentile may be 10%, 15%, 20%, 25% and 30%, etc.), otherstatistical measures of central tendency (e.g., median or mode),dispersion (e.g., mean deviation, standard deviation, variance,interquartile deviations, range), etc. Further, each of the one or moremetrics may be location specific. For example, some metrics may becomputed from signals recorded, or monitored, from electrodes positionedabout a selected area of the patient such as, e.g., the left side of thepatient, the right side of the patient, etc.

In at least one embodiment, one or both of the computing apparatus 140and the remote computing device 160 may be a server, a personalcomputer, a tablet computer, a mobile device, and a cellular telephone.The computing apparatus 140 may be configured to receive input frominput apparatus 142 (e.g., a keyboard) and transmit output to thedisplay apparatus 130, and the remote computing device 160 may beconfigured to receive input from input apparatus 162 (e.g., atouchscreen) and transmit output to the display apparatus 170. One orboth of the computing apparatus 140 and the remote computing device 160may include data storage that may allow for access to processingprograms or routines and/or one or more other types of data, e.g., foranalyzing a plurality of electrical signals captured by the electrodeapparatus 110, for determining QRS onsets, QRS offsets, medians, modes,averages, peaks or maximum values, valleys or minimum values, fordetermining electrical activation times, for driving a graphical userinterface configured to noninvasively assist a user in configuring oneor more pacing parameters, or settings, such as, e.g., pacing rate,atrial pacing rate ventricular pacing rate, A-V interval, V-V interval,pacing pulse width, pacing vector, multipoint pacing vector (e.g., leftventricular vector quad lead), pacing voltage, pacing configuration(e.g., biventricular pacing, right ventricle only pacing, left ventricleonly pacing, etc.), and arrhythmia detection and treatment, rateadaptive settings and performance, etc.

The computing apparatus 140 may be operatively coupled to the inputapparatus 142 and the display apparatus 130 to, e.g., transmit data toand from each of the input apparatus 142 and the display apparatus 130,and the remote computing device 160 may be operatively coupled to theinput apparatus 162 and the display apparatus 170 to, e.g., transmitdata to and from each of the input apparatus 162 and the displayapparatus 170. For example, the computing apparatus 140 and the remotecomputing device 160 may be electrically coupled to the input apparatus142, 162 and the display apparatus 130, 170 using, e.g., analogelectrical connections, digital electrical connections, wirelessconnections, bus-based connections, network-based connections,internet-based connections, etc. As described further herein, a user mayprovide input to the input apparatus 142, 162 to view and/or select oneor more pieces of configuration information related to the cardiactherapy delivered by cardiac therapy apparatus such as, e.g., animplantable medical device.

Although as depicted the input apparatus 142 is a keyboard and the inputapparatus 162 is a touchscreen, it is to be understood that the inputapparatus 142, 162 may include any apparatus capable of providing inputto the computing apparatus 140 and the computing device 160 to performthe functionality, methods, and/or logic described herein. For example,the input apparatus 142, 162 may include a keyboard, a mouse, atrackball, a touchscreen (e.g., capacitive touchscreen, a resistivetouchscreen, a multi-touch touchscreen, etc.), etc. Likewise, thedisplay apparatus 130, 170 may include any apparatus capable ofdisplaying information to a user, such as a graphical user interface132, 172 including electrode status information, graphical maps ofelectrical activation, a plurality of signals for the externalelectrodes over one or more heartbeats, QRS complexes, various cardiactherapy scenario selection regions, various rankings of cardiac therapyscenarios, various pacing parameters, electrical heterogeneityinformation (EHI), textual instructions, graphical depictions of anatomyof a human heart, images or graphical depictions of the patient's heart,graphical depictions of locations of one or more electrodes, graphicaldepictions of a human torso, images or graphical depictions of thepatient's torso, graphical depictions or actual images of implantedelectrodes and/or leads, etc. Further, the display apparatus 130, 170may include a liquid crystal display, an organic light-emitting diodescreen, a touchscreen, a cathode ray tube display, etc.

The processing programs or routines stored and/or executed by thecomputing apparatus 140 and the remote computing device 160 may includeprograms or routines for computational mathematics, matrix mathematics,decomposition algorithms, compression algorithms (e.g., data compressionalgorithms), calibration algorithms, image construction algorithms,signal processing algorithms (e.g., various filtering algorithms,Fourier transforms, fast Fourier transforms, etc.), standardizationalgorithms, comparison algorithms, vector mathematics, or any otherprocessing used to implement one or more illustrative methods and/orprocesses described herein. Data stored and/or used by the computingapparatus 140 and the remote computing device 160 may include, forexample, electrical signal/waveform data from the electrode apparatus110 (e.g., a plurality of QRS complexes), electrical activation timesfrom the electrode apparatus 110, cardiac sound/signal/waveform datafrom acoustic sensors, graphics (e.g., graphical elements, icons,buttons, windows, dialogs, pull-down menus, graphic areas, graphicregions, 3D graphics, etc.), graphical user interfaces, results from oneor more processing programs or routines employed according to thedisclosure herein (e.g., electrical signals, electrical heterogeneityinformation, etc.), or any other data that may be used for carrying outthe one and/or more processes or methods described herein.

In one or more embodiments, the illustrative systems, methods, andinterfaces may be implemented using one or more computer programsexecuted on programmable computers, such as computers that include, forexample, processing capabilities, data storage (e.g., volatile ornon-volatile memory and/or storage elements), input devices, and outputdevices. Program code and/or logic described herein may be applied toinput data to perform functionality described herein and generatedesired output information. The output information may be applied asinput to one or more other devices and/or methods as described herein oras would be applied in a known fashion.

The one or more programs used to implement the systems, methods, and/orinterfaces described herein may be provided using any programmablelanguage, e.g., a high-level procedural and/or object orientatedprogramming language that is suitable for communicating with a computersystem. Any such programs may, for example, be stored on any suitabledevice, e.g., a storage media, that is readable by a general or specialpurpose program running on a computer system (e.g., including processingapparatus) for configuring and operating the computer system when thesuitable device is read for performing the procedures described herein.In other words, at least in one embodiment, the illustrative systems,methods, and interfaces may be implemented using a computer readablestorage medium, configured with a computer program, where the storagemedium so configured causes the computer to operate in a specific andpredefined manner to perform functions described herein. Further, in atleast one embodiment, the illustrative systems, methods, and interfacesmay be described as being implemented by logic (e.g., object code)encoded in one or more non-transitory media that includes code forexecution and, when executed by a processor or processing circuitry, isoperable to perform operations such as the methods, processes, and/orfunctionality described herein.

The computing apparatus 140 and the remote computing device 160 may be,for example, any fixed or mobile computer system (e.g., a controller, amicrocontroller, a personal computer, minicomputer, tablet computer,etc.). The exact configurations of the computing apparatus 140 and theremote computing device 160 are not limiting, and essentially any devicecapable of providing suitable computing capabilities and controlcapabilities (e.g., signal analysis, mathematical functions such asmedians, modes, averages, maximum value determination, minimum valuedetermination, slope determination, minimum slope determination, maximumslope determination, graphics processing, etc.) may be used. Asdescribed herein, a digital file may be any medium (e.g., volatile ornon-volatile memory, a CD-ROM, a punch card, magnetic recordable tape,etc.) containing digital bits (e.g., encoded in binary, trinary, etc.)that may be readable and/or writeable by the computing apparatus 140 andthe remote computing device 160 described herein. Also, as describedherein, a file in user-readable format may be any representation of data(e.g., ASCII text, binary numbers, hexadecimal numbers, decimal numbers,graphically, etc.) presentable on any medium (e.g., paper, a display,etc.) readable and/or understandable by a user.

In view of the above, it will be readily apparent that the functionalityas described in one or more embodiments according to the presentdisclosure may be implemented in any manner as would be known to oneskilled in the art. As such, the computer language, the computer system,or any other software/hardware which is to be used to implement theprocesses described herein shall not be limiting on the scope of thesystems, processes, or programs (e.g., the functionality provided bysuch systems, processes, or programs) described herein.

The illustrative electrode apparatus 110 may be configured to measurebody-surface potentials of a patient 14 and, more particularly,torso-surface potentials of a patient 14. As shown in FIG. 2, theillustrative electrode apparatus 110 may include a set, or array, ofexternal electrodes 112, a strap 113, and interface/amplifier circuitry116. The electrodes 112 may be attached, or coupled, to the strap 113and the strap 113 may be configured to be wrapped around the torso of apatient 14 such that the electrodes 112 surround the patient's heart. Asfurther illustrated, the electrodes 112 may be positioned around thecircumference of a patient 14, including the posterior, lateral,posterolateral, anterolateral, and anterior locations of the torso of apatient 14.

The illustrative electrode apparatus 110 may be further configured tomeasure, or monitor, sounds from at least one or both the patient 14. Asshown in FIG. 2, the illustrative electrode apparatus 110 may include aset, or array, of acoustic sensors 120 attached, or coupled, to thestrap 113. The strap 113 may be configured to be wrapped around thetorso of a patient 14 such that the acoustic sensors 120 surround thepatient's heart. As further illustrated, the acoustic sensors 120 may bepositioned around the circumference of a patient 14, including theposterior, lateral, posterolateral, anterolateral, and anteriorlocations of the torso of a patient 14.

Further, the electrodes 112 and the acoustic sensors 120 may beelectrically connected to interface/amplifier circuitry 116 via wiredconnection 118. The interface/amplifier circuitry 116 may be configuredto amplify the signals from the electrodes 112 and the acoustic sensors120 and provide the signals to one or both of the computing apparatus140 and the remote computing device 160. Other illustrative systems mayuse a wireless connection to transmit the signals sensed by electrodes112 and the acoustic sensors 120 to the interface/amplifier circuitry116 and, in turn, to one or both of the computing apparatus 140 and theremote computing device 160, e.g., as channels of data. In one or moreembodiments, the interface/amplifier circuitry 116 may be electricallycoupled to the computing apparatus 140 using, e.g., analog electricalconnections, digital electrical connections, wireless connections,bus-based connections, network-based connections, internet-basedconnections, etc.

Although in the example of FIG. 2 the electrode apparatus 110 includes astrap 113, in other examples any of a variety of mechanisms, e.g., tapeor adhesives, may be employed to aid in the spacing and placement ofelectrodes 112 and the acoustic sensors 120. In some examples, the strap113 may include an elastic band, strip of tape, or cloth. Further, insome examples, the strap 113 may be part of, or integrated with, a pieceof clothing such as, e.g., a t-shirt. In other examples, the electrodes112 and the acoustic sensors 120 may be placed individually on the torsoof a patient 14. Further, in other examples, one or both of theelectrodes 112 (e.g., arranged in an array) and the acoustic sensors 120(e.g., also arranged in an array) may be part of, or located within,patches, vests, and/or other manners of securing the electrodes 112 andthe acoustic sensors 120 to the torso of the patient 14. Still further,in other examples, one or both of the electrodes 112 and the acousticsensors 120 may be part of, or located within, two sections of materialor two patches. One of the two patches may be located on the anteriorside of the torso of the patient 14 (to, e.g., monitor electricalsignals representative of the anterior side of the patient's heart,measure surrogate cardiac electrical activation times representative ofthe anterior side of the patient's heart, monitor or measure sounds ofthe anterior side of the patient, etc.) and the other patch may belocated on the posterior side of the torso of the patient 14 (to, e.g.,monitor electrical signals representative of the posterior side of thepatient's heart, measure surrogate cardiac electrical activation timesrepresentative of the posterior side of the patient's heart, monitor ormeasure sounds of the posterior side of the patient, etc.). And stillfurther, in other examples, one or both of the electrodes 112 and theacoustic sensors 120 may be arranged in a top row and bottom row thatextend from the anterior side of the patient 14 across the left side ofthe patient 14 to the posterior side of the patient 14. Yet stillfurther, in other examples, one or both of the electrodes 112 and theacoustic sensors 120 may be arranged in a curve around the armpit areaand may have an electrode/sensor-density that less dense on the rightthorax that the other remaining areas.

The electrodes 112 may be configured to surround the heart of thepatient 14 and record, or monitor, the electrical signals associatedwith the depolarization and repolarization of the heart after thesignals have propagated through the torso of a patient 14. Each of theelectrodes 112 may be used in a unipolar configuration to sense thetorso-surface potentials that reflect the cardiac signals. Theinterface/amplifier circuitry 116 may also be coupled to a return orindifferent electrode (not shown) that may be used in combination witheach electrode 112 for unipolar sensing.

In some examples, there may be about 12 to about 50 electrodes 112 andabout 12 to about 50 acoustic sensors 120 spatially distributed aroundthe torso of a patient. Other configurations may have more or fewerelectrodes 112 and more or fewer acoustic sensors 120. It is to beunderstood that the electrodes 112 and acoustic sensors 120 may not bearranged or distributed in an array extending all the way around orcompletely around the patient 14. Instead, the electrodes 112 andacoustic sensors 120 may be arranged in an array that extends only partof the way or partially around the patient 14. For example, theelectrodes 112 and acoustic sensors 120 may be distributed on theanterior, posterior, and left sides of the patient with less or noelectrodes and acoustic sensors proximate the right side (includingposterior and anterior regions of the right side of the patient).

The computing apparatus 140 may record and analyze the torso-surfacepotential signals sensed by electrodes 112 and the sound signals sensedby the acoustic sensors 120, which are amplified/conditioned by theinterface/amplifier circuitry 116. The computing apparatus 140 may beconfigured to analyze the electrical signals from the electrodes 112 toprovide electrocardiogram (ECG) signals, information, or data from thepatient's heart as will be further described herein. The computingapparatus 140 may be configured to analyze the electrical signals fromthe acoustic sensors 120 to provide sound signals, information, or datafrom the patient's body and/or devices implanted therein (such as a leftventricular assist device).

Additionally, the computing apparatus 140 and the remote computingdevice 160 may be configured to provide graphical user interfaces 132,172 depicting various information related to the electrode apparatus 110and the data gathered, or sensed, using the electrode apparatus 110. Forexample, the graphical user interfaces 132, 172 may depict ECGsincluding QRS complexes obtained using the electrode apparatus 110 andsound data including sound waves obtained using the acoustic sensors 120as well as other information related thereto. Illustrative systems andmethods may noninvasively use the electrical information collected usingthe electrode apparatus 110 and the sound information collected usingthe acoustic sensors 120 to evaluate a patient's cardiac health and toevaluate and configure cardiac therapy being delivered to the patient.

Further, the electrode apparatus 110 may further include referenceelectrodes and/or drive electrodes to be, e.g. positioned about thelower torso of the patient 14, that may be further used by the system100. For example, the electrode apparatus 110 may include threereference electrodes, and the signals from the three referenceelectrodes may be combined to provide a reference signal. Further, theelectrode apparatus 110 may use of three caudal reference electrodes(e.g., instead of standard references used in a Wilson Central Terminal)to get a “true” unipolar signal with less noise from averaging threecaudally located reference signals.

FIG. 3 illustrates another illustrative electrode apparatus 110 thatincludes a plurality of electrodes 112 configured to surround the heartof the patient 14 and record, or monitor, the electrical signalsassociated with the depolarization and repolarization of the heart afterthe signals have propagated through the torso of the patient 14 and aplurality of acoustic sensors 120 configured to surround the heart ofthe patient 14 and record, or monitor, the sound signals associated withthe heart after the signals have propagated through the torso of thepatient 14. The electrode apparatus 110 may include a vest 114 uponwhich the plurality of electrodes 112 and the plurality of acousticsensors 120 may be attached, or to which the electrodes 112 and theacoustic sensors 120 may be coupled. In at least one embodiment, theplurality, or array, of electrodes 112 may be used to collect electricalinformation such as, e.g., surrogate electrical activation times.Similar to the electrode apparatus 110 of FIG. 2, the electrodeapparatus 110 of FIG. 3 may include interface/amplifier circuitry 116electrically coupled to each of the electrodes 112 and the acousticsensors 120 through a wired connection 118 and be configured to transmitsignals from the electrodes 112 and the acoustic sensors 120 tocomputing apparatus 140. As illustrated, the electrodes 112 and theacoustic sensors 120 may be distributed over the torso of a patient 14,including, for example, the posterior, lateral, posterolateral,anterolateral, and anterior locations of the torso of a patient 14.

The vest 114 may be formed of fabric with the electrodes 112 and theacoustic sensors 120 attached to the fabric. The vest 114 may beconfigured to maintain the position and spacing of electrodes 112 andthe acoustic sensors 120 on the torso of the patient 14. Further, thevest 114 may be marked to assist in determining the location of theelectrodes 112 and the acoustic sensors 120 on the surface of the torsoof the patient 14. In some examples, there may be about 25 to about 256electrodes 112 and about 25 to about 256 acoustic sensors 120distributed around the torso of the patient 14, though otherconfigurations may have more or fewer electrodes 112 and more or feweracoustic sensors 120.

The illustrative systems and methods may be used to provide noninvasiveassistance to a user in the evaluation of a patient's cardiac healthand/or evaluation and configuration of cardiac therapy being presentlydelivered to the patient (e.g., by an implantable medical devicedelivering pacing therapy, by a LVAD, etc.). Further, it is to beunderstood that the computing apparatus 140 and the remote computingdevice 160 may be operatively coupled to each other in a plurality ofdifferent ways so as to perform, or execute, the functionality describedherein. For example, in the embodiment depicted, the computing device140 may be wireless operably coupled to the remote computing device 160as depicted by the wireless signal lines emanating therebetween.Additionally, as opposed to wireless connections, one or more of thecomputing apparatus 140 and the remoting computing device 160 may beoperably coupled through one or wired electrical connections.

According to embodiments described herein, the illustrative system 100,which may be referred to as an ECG belt system, may be used with cardiactherapy systems and devices (e.g., CRT pacing devices) to calculatevarious metrics related to the cardiac health of a patient (e.g., thestandard deviation of activation times (SDAT)) across one or morecardiac cycles (or heart beats), and in particular, based on activationtimes or other data gathered during each QRS event of the cardiac cycle(heart beat). According to various embodiments, the illustrative system100 may be used to calculate, or generate, electrical heterogeneityinformation such as, e.g., SDAT, of cardiac cycles during delivery ofCRT (e.g., the SDAT for cardiac cycles where CRT paces are delivered).For example, the illustrative system 100 may be used to calculateelectrical heterogeneity information for cardiac cycles duringbiventricular and/or left ventricular pacing. Further, embodimentsdescribed herein may be used to evaluate a patient's cardiac healthand/or non-CRT pacing. If electrical heterogeneity information isinaccurate, the output of the illustrative system 100 could bemisleading, which could potentially impact lead placement (e.g., animplantable lead not being placed at an optimal spot) and/or optimaldevice programming. For example, if the SDAT is inaccurate, the SDAT maybe artificially low, which may cause a clinician to not relocatecurrently positioned lead as opposed to repositioning the lead to obtaina better response

According to various configurations, the ECG belt and an associatedminiaturized amplifier can be portable such that a patient does not haveto be at a clinic to measure electrical activity and to optimize variousparameters of an implantable medical device (IMD). The ECG belt andportable amplifier system may be used as an external smart portablediagnostic system that can be used to in-home monitoring in patientswith or without implantable devices. In some cases, the portableamplifier may be able to communicate directly with an IMD to optimizepacing parameters and/or to check parameters to flag potential issuesfor further follow-up. The portable amplifier may be able to performtasks automatically without the need for a programmer.

An exemplary system with a portable amplifier is shown in FIG. 4A. Inthis example, the patient 410 has an ECG belt 430 and an optional IMD420. The ECG belt has an associated portable amplifier 440 that isoperatively coupled to the ECG belt 430 and the IMD 420. The portableamplifier 440 has an optimization module that may be used to optimizeparameters of the pacing device. A device check module 444 may be usedto check device parameters of one or more of the IMD and the ECG belt.

FIGS. 4B and 4C illustrate another example of an ECG belt with aportable amplifier in accordance with embodiments described herein. Inthis example, the ECG belt 460 has a C-shaped design vest and/or beltwith a portable amplifier 465. FIG. 4B illustrates a front view of theECG belt 460 and FIG. 4C shows a rear view. In this example, the ECGbelt 460 wraps around the left side of the torso from the sternum on thefront to the spine on the rear. According to various embodiments, thevest and/or belt is made with a flexible and/or stretchable materialwith the electrodes 462 are sewn on or incorporated by other means(e.g., adhesive). The flexible material allows for fitting bodies ofdifferent shapes and/or sizes. The ECG band 460 may include anatomicmarkers such as left anterior, posterior, sternum, and/or spine to helpthe patient and/or user to orient the belt 460 correctly.

According to carious embodiments, the ECG belt 460 may include at leasttwo rows of reusable electrodes 462. There may be 10 electrodes in eachrow (e.g., five on the front of the body from the sternum to the leftposterior axillary line and five on the back of the body from the leftposterior axillary line to the spine). The built-in amplifier may beconfigured to record at least 5 seconds of ECG data and transmitting thedata to a cloud for processing of left heart electrical dyssynchrony(e.g., LVAT) or other diagnostic metrics described herein. An exemplarymethod 500 for using an ECG belt with a portable amplifier in accordancewith embodiments described herein is shown in FIG. 5. Electricalactivity from tissue of a patient is monitored 510 using a plurality ofexternal electrodes to generate a plurality of electrical signals overtime. The plurality of electrodes may be external surface electrodesconfigured in a band or a vest similar to what is described herein withrespect to FIGS. 1-3. Each of the electrodes may be positioned orlocated about the torso of the patient so as to monitor electricalactivity (e.g., acquire torso-potentials) from a plurality of differentlocations about the torso of the patient. Each of the differentlocations where the electrodes are located may correspond to theelectrical activation of different portions or regions of cardiac tissueof the patient's heart.

At least one of optimizing device parameters and determining cardiacsynchrony is performed 520. The device parameters may comprise one ormore of pacing parameters such as pacing rate, atrial pacing rate,ventricular pacing rate, A-V interval, V-V interval, pacing pulse width,pacing vector, multipoint pacing timings, and pacing voltage. While anoptimization process and a cardiac synchrony assessment are performed inthis example, it is to be understood that other tests may be performed.In some cases, the portable amplifier system performs tests in apredetermined sequence. The tests may be conducted at predeterminedtimes.

According to various configurations, determining cardiac synchrony isperformed automatically without a programmer. For example, the cardiacsynchrony assessment may be done at predetermined intervals of timeand/or at predetermined times of day. In some cases, the cardiacsynchrony assessment is performed based on a detected physiologicalparameter and/or based on patient indicated symptoms. The physiologicalparameter may include one or more of a heart rate, a breathing rate,indication of fluid retention status (thoracic impedance, pressure,etc), blood pressure, arrhythmia status, changes in heart sounds,indicators of phrenic nerve stimulation (e.g. via acoustic/heart soundssensors), a possible fall, posture, a respiration rate, and/or activitylevel.

According to various configurations, the portable amplifier isconfigured to transmit a summary of the findings of all the routinetests on a display device. The display device may include a smart devicehaving security encryption. For example, the display device may includea smart phone, a tablet, and/or a smart watch. In some cases, an optionis provided to print out a report. The report may contain flags onissues (e.g. battery life, problems with lead impedances and/orcapture). It may also provide feedback to the patient via his or hersmart phone, smart watch or other smart devices with proper securityencryption. With an in home portable smart amplifier system, such checkscan be done periodically at home or during various ambulatoryconditions, and/or during exercise. The information may be transmittedautomatically when an associated smart device is available and/or thetransmission may be initiated by a user. The transmission may occur viaa wired connection and/or via a wireless connection. In some cases, theportable amplifier is configured to transmit the information to adisplay device at a clinic.

FIG. 6 shows a more detailed method for using an ECG belt with aportable amplifier in accordance with embodiments described herein isshown. Electrical activity from tissue of a patient is monitored 550.

As described in conjunction with FIG. 5, an optimization process may beperformed based in the monitored electrical activity. The optimizationprocess may comprise scanning 570 parameter values of one or moreparameters. A value is selected 580 for each scanned parameter thatresults in the highest electrical synchrony.

The cardiac synchrony assessment may include automatically determining590 one or more pacing device metrics based on one or more measuredparameters. The pacing device metrics comprise one or more of pacingthresholds, pacing timings, lead impedances, and a determination ofeffective capture. According to various configurations, metricsdetermined using electrical activity sensed from the ECG belt mayprovide independent confirmation of electrical events like basic captureof RV/LV leads, for example. QRS templates from multiple ECGs (based onstandard deviation of some or all of the 40 ECG signals) may becollected for baseline/intrinsic rhythm. Parameters such as ventricularrates may be determined from time-intervals between successive QRScomplexes.

According to various configurations, if the one or more pacing metricsare outside of a threshold range, the portable amplifier may issue analert and/or a note to follow/up. The alert and/or follow-up note may betransmitted directly to a patient smart device and/or to an associatedmedical institution. Depending on the value of the metric, the alert maybe issued immediately to a medical institution. According to variousconfigurations, an alert may be sent if progressively worseningdyssynchrony is detected as this may be an indicator of heart failure.In some cases, the alert may be sent if indicators of arrhythmias aredetected such as QT dispersion increasing.

The ECG belt and portable amplifier system may determine lack of capturefor a pacing lead when QRS templates during pacing has a high degree ofcorrelation with previously collected baseline/intrinsic QRS templates.For example, a lack of pace capture may be determined if the rate fromsuccessive QRS intervals during pacing lags behind the overdrive pacingrate. This avoids manual testing or testing with an additionalprogrammer device.

FIG. 7 show an example of determining if capture has occurred atdifferent pacing outputs. The intrinsic surface QRS template measuredwith the ECG belt is shown in 610. The intrinsic surface QRS template iscollected at a time when there is no pacing therapy. A paced surface QRStemplate is determined at different pacing outputs. In this example, thetemplates are determined at pacing outputs of 2.5 V 620, 2.0 V 630, and1.5V 640. Each of the paced templates 620, 630, 640 are compared to theintrinsic template 610. As can be observed, the templates resulting fromthe 2.5V pace 620 and the 2.0 V pace 630 do not match the intrinsictemplate 610. It is thus determined that capture has occurred for the2.5 V pace 620 and the 2.0 V pace. The template resulting from the 1.5Vpace 640 does match the intrinsic QRS template 610. It is determinedthat the 1.5V pace 640 does not result in capture because it matches theintrinsic QRS template 610.

According to various configurations, the ECG belt and portable amplifiersystem may be used for collecting cardiac dyssynchrony data. Thedyssynchrony data can be transmitted to a smart device with a requisiteamount of security encryption and/or can be transmitted directly to amedical institution.

An exemplary system for collecting cardiac dyssynchrony data using aportable ECG belt and a portable amplifier is shown in FIG. 8. In thisexample, the patient 710 has an ECG belt 730 and an optional IMD 720.The ECG belt has an associated portable amplifier 740 that isoperatively coupled to the ECG belt 730 and the IMD 720. The portableamplifier 740 may be coupled to a smart device 760 of the patient, forexample. In some cases, the portable amplifier 740 and/or the IMD 720 isconfigured to transmit collected data to a secure medical device 750.The secure medical device 750 may be configured to store intrinsicand/or paced maps that are produced using the data collected from theECG belt. 730. The portable amplifier 740 and/or the secure medicaldevice 750 may be configured to transmit collected data to a medicalinstitution for follow-up.

An exemplary method 800 for using an ECG belt with a portable amplifierto collect cardiac dyssynchrony data in accordance with embodimentsdescribed herein is shown in FIG. 9. Electrical activity from tissue ofa patient is monitored 810 using a plurality of external electrodes togenerate a plurality of electrical signals.

One or more parameters of the patient are measured 820 based on theplurality of electrical signals. Examples of such parameters may includemetrics related to cardiac dyssynchrony based on dispersion metrics ofelectrical activation and repolarization times or average of such timesmeasured over all electrodes or a subset of electrodes proximate aspecific anatomic region or related measures including QRS duration, QRSarea.

One or more metrics of the patient are determined 830 based on the oneor more parameters. The one or more metrics may comprise one or moreindicators of cardiac dyssynchrony, one or more indicators of a risk ofarrhythmias, and/or one or more indicators of development of newconduction blocks and/or disturbances. The one or more metrics may becalculated by determining if one or more of the measured parameters isbeyond a predetermined threshold and/or beyond a previous measurementunder substantially the same conditions. In some cases, the one or moremetrics comprise one or more of standard deviation of activation times(SDAT), average of left ventricular activation times (LVAT), standarddeviation of left ventricular activation times, standard deviation ofright ventricular activation times, QT dispersion, activation recoveryinterval over multiple ECG electrodes, and recovery time. According tovarious configurations, the ECG belt and the portable amplifier systemis configured to do stress testing while the patient exercises (e.g.,climbing stairs). In this example, the system can detect markers ofischemia like ST segment elevation, for example.

The portable amplifier may be configured to issue an alert to the smartdevice and/or to the secure medical device if indicators of cardiacdyssynchrony and/or a risk of arrhythmias is detected. In some cases,the system may be configured to send alerts to one or more nearestclinics if thresholds predictive of an impending event are triggered.

In some cases, the portable amplifier communicates with the IMD tochange one or more device parameters. The amplifier may optimize the oneor more device parameters to reduce and/or minimize electricaldyssynchrony

A summary of the one more metrics may be transmitted 840 to a smartdevice with security encryption. The smart device may include one ormore secure medical devices.

FIG. 10 illustrates an example of a QRS complex. The QT interval 920 maybe determined by the portable amplifier for diagnostic purposes.Similarly the activation-recovery interval 910 may be determined. Theactivation time corresponds to the minimum change over time in the QRScomplex. The recovery time corresponds to the time where the maximumchange over time occurs during the T wave. These parameters may bedetermined by the portable amplifier for diagnostic purposes and/or as apart of an optimization process.

Illustrative cardiac therapy systems and devices may be furtherdescribed herein with reference to FIGS. 11-13 that may utilizes theillustrative systems, interfaces, methods, and processes describedherein with respect to FIGS. 1-10.

FIG. 11 is a conceptual diagram illustrating an illustrative therapysystem 10 that may be used to deliver pacing therapy to a patient 14.Patient 14 may, but not necessarily, be a human. The therapy system 10may include an implantable medical device 16 (IMD), which may be coupledto leads 18, 20, 22. The IMD 16 may be, e.g., an implantable pacemaker,cardioverter, and/or defibrillator, that delivers, or provides,electrical signals (e.g., paces, etc.) to and/or senses electricalsignals from the heart 12 of the patient 14 via electrodes coupled toone or more of the leads 18, 20, 22.

The leads 18, 20, 22 extend into the heart 12 of the patient 14 to senseelectrical activity of the heart 12 and/or to deliver electricalstimulation to the heart 12. In the example shown in FIG. 11, the rightventricular (RV) lead 18 extends through one or more veins (not shown),the superior vena cava (not shown), and the right atrium 26, and intothe right ventricle 28. The left ventricular (LV) coronary sinus lead 20extends through one or more veins, the vena cava, the right atrium 26,and into the coronary sinus 30 to a region adjacent to the free wall ofthe left ventricle 32 of the heart 12. The right atrial (RA) lead 22extends through one or more veins and the vena cava, and into the rightatrium 26 of the heart 12.

The IMD 16 may sense, among other things, electrical signals attendantto the depolarization and repolarization of the heart 12 via electrodescoupled to at least one of the leads 18, 20, 22. In some examples, theIMD 16 provides pacing therapy (e.g., pacing pulses) to the heart 12based on the electrical signals sensed within the heart 12. The IMD 16may be operable to adjust one or more parameters associated with thepacing therapy such as, e.g., A-V delay and other various timings, pulsewidth, amplitude, voltage, burst length, pacing vector, etc. Further,the IMD 16 may be operable to use various electrode configurations todeliver pacing therapy, which may be unipolar, bipolar, quadripolar, orfurther multipolar. For example, a multipolar lead may include severalelectrodes that can be used for delivering pacing therapy. Hence, amultipolar lead system may provide, or offer, multiple electricalvectors to pace from. A pacing vector may include at least one cathode,which may be at least one electrode located on at least one lead, and atleast one anode, which may be at least one electrode located on at leastone lead (e.g., the same lead, or a different lead) and/or on thecasing, or can, of the IMD. While improvement in cardiac function as aresult of the pacing therapy may primarily depend on the cathode, theelectrical parameters like impedance, pacing threshold voltage, currentdrain, longevity, etc. may be more dependent on the pacing vector, whichincludes both the cathode and the anode. The IMD 16 may also providedefibrillation therapy and/or cardioversion therapy via electrodeslocated on at least one of the leads 18, 20, 22. Further, the IMD 16 maydetect arrhythmia of the heart 12, such as fibrillation of theventricles 28, 32, and deliver defibrillation therapy to the heart 12 inthe form of electrical pulses. In some examples, IMD 16 may beprogrammed to deliver a progression of therapies, e.g., pulses withincreasing energy levels, until a fibrillation of heart 12 is stopped.

FIGS. 12A-12B are conceptual diagrams illustrating the IMD 16 and theleads 18, 20, 22 of therapy system 10 of FIG. 11 in more detail. Theleads 18, 20, 22 may be electrically coupled to a therapy deliverymodule (e.g., for delivery of pacing therapy), a sensing module (e.g.,for sensing one or more signals from one or more electrodes), and/or anyother modules of the IMD 16 via a connector block 34. In some examples,the proximal ends of the leads 18, 20, 22 may include electricalcontacts that electrically couple to respective electrical contactswithin the connector block 34 of the IMD 16. In addition, in someexamples, the leads 18, 20, 22 may be mechanically coupled to theconnector block 34 with the aid of set screws, connection pins, oranother suitable mechanical coupling mechanism.

Each of the leads 18, 20, 22 includes an elongated insulative lead body,which may carry a number of conductors (e.g., concentric coiledconductors, straight conductors, etc.) separated from one another byinsulation (e.g., tubular insulative sheaths). In the illustratedexample, bipolar electrodes 40, 42 are located proximate to a distal endof the lead 18. In addition, bipolar electrodes 44, 45, 46, 47 arelocated proximate to a distal end of the lead 20 and bipolar electrodes48, 50 are located proximate to a distal end of the lead 22.

The electrodes 40, 44, 45, 46, 47, 48 may take the form of ringelectrodes, and the electrodes 42, 50 may take the form of extendablehelix tip electrodes mounted retractably within the insulative electrodeheads 52, 54, 56, respectively. In some cases, the electrodes 42, 50 arefixed helix and/or passive lead electrodes. Each of the electrodes 40,42, 44, 45, 46, 47, 48, 50 may be electrically coupled to a respectiveone of the conductors (e.g., coiled and/or straight) within the leadbody of its associated lead 18, 20, 22, and thereby coupled to arespective one of the electrical contacts on the proximal end of theleads 18, 20, 22.

Additionally, electrodes 44, 45, 46 and 47 may have an electrode surfacearea of about 5.3 mm² to about 5.8 mm². Electrodes 44, 45, 46, and 47may also be referred to as LV1, LV2, LV3, and LV4, respectively. The LVelectrodes (i.e., left ventricle electrode 1 (LV1) 44, left ventricleelectrode 2 (LV2) 45, left ventricle electrode 3 (LV3) 46, and leftventricle 4 (LV4) 47 etc.) on the lead 20 can be spaced apart atvariable distances. For example, electrode 44 may be a distance of,e.g., about 21 millimeters (mm), away from electrode 45, electrodes 45and 46 may be spaced a distance of, e.g. about 1.3 mm to about 1.5 mm,away from each other, and electrodes 46 and 47 may be spaced a distanceof, e.g. 20 mm to about 21 mm, away from each other.

The electrodes 40, 42, 44, 45, 46, 47, 48, 50 may further be used tosense electrical signals (e.g., morphological waveforms withinelectrograms (EGM)) attendant to the depolarization and repolarizationof the heart 12. The electrical signals are conducted to the IMD 16 viathe respective leads 18, 20, 22. In some examples, the IMD 16 may alsodeliver pacing pulses via the electrodes 40, 42, 44, 45, 46, 47, 48, 50to cause depolarization of cardiac tissue of the patient's heart 12. Insome examples, as illustrated in FIG. 12A, the IMD 16 includes one ormore housing electrodes, such as housing electrode 58, which may beformed integrally with an outer surface of a housing 60 (e.g.,hermetically-sealed housing) of the IMD 16 or otherwise coupled to thehousing 60. Any of the electrodes 40, 42, 44, 45, 46, 47, 48, 50 may beused for unipolar sensing or pacing in combination with the housingelectrode 58. It is generally understood by those skilled in the artthat other electrodes can also be selected to define, or be used for,pacing and sensing vectors. Further, any of electrodes 40, 42, 44, 45,46, 47, 48, 50, 58, when not being used to deliver pacing therapy, maybe used to sense electrical activity during pacing therapy.

As described in further detail with reference to FIG. 12A, the housing60 may enclose a therapy delivery module that may include a stimulationgenerator for generating cardiac pacing pulses and defibrillation orcardioversion shocks, as well as a sensing module for monitoring theelectrical signals of the patient's heart (e.g., the patient's heartrhythm). The leads 18, 20, 22 may also include elongated electrodes 62,64, 66, respectively, which may take the form of a coil. The IMD 16 maydeliver defibrillation shocks to the heart 12 via any combination of theelongated electrodes 62, 64, 66 and the housing electrode 58. Theelectrodes 58, 62, 64, 66 may also be used to deliver cardioversionpulses to the heart 12. Further, the electrodes 62, 64, 66 may befabricated from any suitable electrically conductive material, such as,but not limited to, platinum, platinum alloy, and/or other materialsknown to be usable in implantable defibrillation electrodes. Sinceelectrodes 62, 64, 66 are not generally configured to deliver pacingtherapy, any of electrodes 62, 64, 66 may be used to sense electricalactivity and may be used in combination with any of electrodes 40, 42,44, 45, 46, 47, 48, 50, 58. In at least one embodiment, the RV elongatedelectrode 62 may be used to sense electrical activity of a patient'sheart during the delivery of pacing therapy (e.g., in combination withthe housing electrode 58, or defibrillation electrode-to-housingelectrode vector).

The configuration of the illustrative therapy system 10 illustrated inFIGS. 11-13 is merely one example. In other examples, the therapy systemmay include epicardial leads and/or patch electrodes instead of or inaddition to the transvenous leads 18, 20, 22 illustrated in FIG. 11.Additionally, in other examples, the therapy system 10 may be implantedin/around the cardiac space without transvenous leads (e.g.,leadless/wireless pacing systems) or with leads implanted (e.g.,implanted transvenously or using approaches) into the left chambers ofthe heart (in addition to or replacing the transvenous leads placed intothe right chambers of the heart as illustrated in FIG. 11). Further, inone or more embodiments, the IMD 16 need not be implanted within thepatient 14. For example, the IMD 16 may deliver various cardiactherapies to the heart 12 via percutaneous leads that extend through theskin of the patient 14 to a variety of positions within or outside ofthe heart 12. In one or more embodiments, the system 10 may utilizewireless pacing (e.g., using energy transmission to the intracardiacpacing component(s) via ultrasound, inductive coupling, RF, etc.) andsensing cardiac activation using electrodes on the can/housing and/or onsubcutaneous leads.

In other examples of therapy systems that provide electrical stimulationtherapy to the heart 12, such therapy systems may include any suitablenumber of leads coupled to the IMD 16, and each of the leads may extendto any location within or proximate to the heart 12. For example, otherexamples of therapy systems may include three transvenous leads locatedas illustrated in FIGS. 11-13. Still further, other therapy systems mayinclude a single lead that extends from the IMD 16 into the right atrium26 or the right ventricle 28, or two leads that extend into a respectiveone of the right atrium 26 and the right ventricle 28.

FIG. 13A is a functional block diagram of one illustrative configurationof the IMD 16. As shown, the IMD 16 may include a control module 81, atherapy delivery module 84 (e.g., which may include a stimulationgenerator), a sensing module 86, and a power source 90.

The control module, or apparatus, 81 may include a processor 80, memory82, and a telemetry module, or apparatus, 88. The memory 82 may includecomputer-readable instructions that, when executed, e.g., by theprocessor 80, cause the IMD 16 and/or the control module 81 to performvarious functions attributed to the IMD 16 and/or the control module 81described herein. Further, the memory 82 may include any volatile,non-volatile, magnetic, optical, and/or electrical media, such as arandom-access memory (RAM), read-only memory (ROM), non-volatile RAM(NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory,and/or any other digital media. An illustrative capture managementmodule may be the left ventricular capture management (LVCM) moduledescribed in U.S. Pat. No. 7,684,863 entitled “LV THRESHOLD MEASUREMENTAND CAPTURE MANAGEMENT” and issued March 23, 2010, which is incorporatedherein by reference in its entirety.

The processor 80 of the control module 81 may include any one or more ofa microprocessor, a controller, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field-programmablegate array (FPGA), and/or equivalent discrete or integrated logiccircuitry. In some examples, the processor 80 may include multiplecomponents, such as any combination of one or more microprocessors, oneor more controllers, one or more DSPs, one or more ASICs, and/or one ormore FPGAs, as well as other discrete or integrated logic circuitry. Thefunctions attributed to the processor 80 herein may be embodied assoftware, firmware, hardware, or any combination thereof.

The control module 81 may control the therapy delivery module 84 todeliver therapy (e.g., electrical stimulation therapy such as pacing) tothe heart 12 according to a selected one or more therapy programs, whichmay be stored in the memory 82. More, specifically, the control module81 (e.g., the processor 80) may control various parameters of theelectrical stimulus delivered by the therapy delivery module 84 such as,e.g., A-V delays, V-V delays, pacing pulses with the amplitudes, pulsewidths, frequency, or electrode polarities, etc., which may be specifiedby one or more selected therapy programs (e.g., A-V and/or V-V delayadjustment programs, pacing therapy programs, pacing recovery programs,capture management programs, etc.). As shown, the therapy deliverymodule 84 is electrically coupled to electrodes 40, 42, 44, 45, 46, 47,48, 50, 58, 62, 64, 66, e.g., via conductors of the respective lead 18,20, 22, or, in the case of housing electrode 58, via an electricalconductor disposed within housing 60 of IMD 16. Therapy delivery module84 may be configured to generate and deliver electrical stimulationtherapy such as pacing therapy to the heart 12 using one or more of theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66.

For example, therapy delivery module 84 may deliver pacing stimulus(e.g., pacing pulses) via ring electrodes 40, 44, 45, 46, 47, 48 coupledto leads 18, 20, 22 and/or helical tip electrodes 42, 50 of leads 18,22. Further, for example, therapy delivery module 84 may deliverdefibrillation shocks to heart 12 via at least two of electrodes 58, 62,64, 66. In some examples, therapy delivery module 84 may be configuredto deliver pacing, cardioversion, or defibrillation stimulation in theform of electrical pulses. In other examples, therapy delivery module 84may be configured deliver one or more of these types of stimulation inthe form of other signals, such as sine waves, square waves, and/orother substantially continuous time signals.

The IMD 16 may further include a switch module 85 and the control module81 (e.g., the processor 80) may use the switch module 85 to select,e.g., via a data/address bus, which of the available electrodes are usedto deliver therapy such as pacing pulses for pacing therapy, or which ofthe available electrodes are used for sensing. The switch module 85 mayinclude a switch array, switch matrix, multiplexer, or any other type ofswitching device suitable to selectively couple the sensing module 86and/or the therapy delivery module 84 to one or more selectedelectrodes. More specifically, the therapy delivery module 84 mayinclude a plurality of pacing output circuits. Each pacing outputcircuit of the plurality of pacing output circuits may be selectivelycoupled, e.g., using the switch module 85, to one or more of theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66 (e.g., a pairof electrodes for delivery of therapy to a bipolar or multipolar pacingvector). In other words, each electrode can be selectively coupled toone of the pacing output circuits of the therapy delivery module usingthe switching module 85.

The sensing module 86 is coupled (e.g., electrically coupled) to sensingapparatus, which may include, among additional sensing apparatus, theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66 to monitorelectrical activity of the heart 12, e.g., electrocardiogram(ECG)/electrogram (EGM) signals, etc. The ECG/EGM signals may be used tomeasure or monitor activation times (e.g., ventricular activationstimes, etc.), heart rate (HR), heart rate variability (HRV), heart rateturbulence (HRT), deceleration/acceleration capacity, decelerationsequence incidence, T-wave alternans (TWA), P-wave to P-wave intervals(also referred to as the P-P intervals or A-A intervals), R-wave toR-wave intervals (also referred to as the R-R intervals or V-Vintervals), P-wave to QRS complex intervals (also referred to as the P-Rintervals, A-V intervals, or P-Q intervals), QRS-complex morphology, STsegment (i.e., the segment that connects the QRS complex and theT-wave), T-wave changes, QT intervals, electrical vectors, etc.

The switch module 85 may also be used with the sensing module 86 toselect which of the available electrodes are used, or enabled, to, e.g.,sense electrical activity of the patient's heart (e.g., one or moreelectrical vectors of the patient's heart using any combination of theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66). Likewise,the switch module 85 may also be used with the sensing module 86 toselect which of the available electrodes are not to be used (e.g.,disabled) to, e.g., sense electrical activity of the patient's heart(e.g., one or more electrical vectors of the patient's heart using anycombination of the electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62,64, 66), etc. In some examples, the control module 81 may select theelectrodes that function as sensing electrodes via the switch modulewithin the sensing module 86, e.g., by providing signals via adata/address bus.

In some examples, sensing module 86 includes a channel that includes anamplifier with a relatively wider pass band than the R-wave or P-waveamplifiers. Signals from the selected sensing electrodes may be providedto a multiplexer, and thereafter converted to multi-bit digital signalsby an analog-to-digital converter for storage in memory 82, e.g., as anelectrogram (EGM). In some examples, the storage of such EGMs in memory82 may be under the control of a direct memory access circuit.

In some examples, the control module 81 may operate as aninterrupt-driven device and may be responsive to interrupts from pacertiming and control module, where the interrupts may correspond to theoccurrences of sensed P-waves and R-waves and the generation of cardiacpacing pulses. Any necessary mathematical calculations may be performedby the processor 80 and any updating of the values or intervalscontrolled by the pacer timing and control module may take placefollowing such interrupts. A portion of memory 82 may be configured as aplurality of recirculating buffers, capable of holding one or moreseries of measured intervals, which may be analyzed by, e.g., theprocessor 80 in response to the occurrence of a pace or sense interruptto determine whether the patient's heart 12 is presently exhibitingatrial or ventricular tachyarrhythmia.

The telemetry module 88 of the control module 81 may include anysuitable hardware, firmware, software, or any combination thereof forcommunicating with another device, such as a programmer. For example,under the control of the processor 80, the telemetry module 88 mayreceive downlink telemetry from and send uplink telemetry to aprogrammer with the aid of an antenna, which may be internal and/orexternal. The processor 80 may provide the data to be uplinked to aprogrammer and the control signals for the telemetry circuit within thetelemetry module 88, e.g., via an address/data bus. In some examples,the telemetry module 88 may provide received data to the processor 80via a multiplexer.

The various components of the IMD 16 are further coupled to a powersource 90, which may include a rechargeable or non-rechargeable battery.A non-rechargeable battery may be selected to last for several years,while a rechargeable battery may be inductively charged from an externaldevice, e.g., on a daily or weekly basis.

FIG. 13B is another embodiment of a functional block diagram for IMD 16that depicts bipolar RA lead 22, bipolar RV lead 18, and bipolar LV CSlead 20 without the LA CS pace/sense electrodes and coupled with animplantable pulse generator (IPG) circuit 31 having programmable modesand parameters of a bi-ventricular DDD/R type known in the pacing art.In turn, the sensor signal processing circuit 91 indirectly couples tothe timing circuit 43 and via data and control bus to microcomputercircuitry 33. The IPG circuit 31 is illustrated in a functional blockdiagram divided generally into a microcomputer circuit 33 and a pacingcircuit 21. The pacing circuit 21 includes the digital controller/timercircuit 43, the output amplifiers circuit 51, the sense amplifierscircuit 55, the RF telemetry transceiver 41, the activity sensor circuit35 as well as a number of other circuits and components described below.vCrystal oscillator circuit 89 provides the basic timing clock for thepacing circuit 21 while battery 29 provides power. Power-on-resetcircuit 87 responds to initial connection of the circuit to the batteryfor defining an initial operating condition and similarly, resets theoperative state of the device in response to detection of a low batterycondition. Reference mode circuit 37 generates stable voltage referenceand currents for the analog circuits within the pacing circuit 21.Analog-to-digital converter (ADC) and multiplexer circuit 39 digitizeanalog signals and voltage to provide, e.g., real time telemetry ofcardiac signals from sense amplifiers 55 for uplink transmission via RFtransmitter and receiver circuit 41. Voltage reference and bias circuit37, ADC and multiplexer 39, power-on-reset circuit 87, and crystaloscillator circuit 89 may correspond to any of those used inillustrative implantable cardiac pacemakers.

If the IPG is programmed to a rate responsive mode, the signals outputby one or more physiologic sensors are employed as a rate controlparameter (RCP) to derive a physiologic escape interval. For example,the escape interval is adjusted proportionally to the patient's activitylevel developed in the patient activity sensor (PAS) circuit 35 in thedepicted, illustrative IPG circuit 31. The patient activity sensor 27 iscoupled to the IPG housing and may take the form of a piezoelectriccrystal transducer. The output signal of the patient activity sensor 27may be processed and used as an RCP. Sensor 27 generates electricalsignals in response to sensed physical activity that are processed byactivity circuit 35 and provided to digital controller/timer circuit 43.Activity circuit 35 and associated sensor 27 may correspond to thecircuitry disclosed in U.S. Pat. No. 5,052,388 entitled “METHOD ANDAPPARATUS FOR IMPLEMENTING ACTIVITY SENSING IN A PULSE GENERATOR” andissued on Oct. 1, 1991 and U.S. Pat. No. 4,428,378 entitled “RATEADAPTIVE PACER” and issued on Jan. 31, 1984, each of which isincorporated herein by reference in its entirety. Similarly, theillustrative systems, apparatus, and methods described herein may bepracticed in conjunction with alternate types of sensors such asoxygenation sensors, pressure sensors, pH sensors, and respirationsensors, for use in providing rate responsive pacing capabilities.Alternately, QT time may be used as a rate indicating parameter, inwhich case no extra sensor is required. Similarly, the illustrativeembodiments described herein may also be practiced in non-rateresponsive pacemakers.

Data transmission to and from the external programmer is accomplished byway of the telemetry antenna 57 and an associated RF transceiver 41,which serves both to demodulate received downlink telemetry and totransmit uplink telemetry. Uplink telemetry capabilities may include theability to transmit stored digital information, e.g., operating modesand parameters, EGM histograms, and other events, as well as real timeEGMs of atrial and/or ventricular electrical activity and marker channelpulses indicating the occurrence of sensed and paced depolarizations inthe atrium and ventricle.

Microcomputer 33 contains a microprocessor 80 and associated systemclock and on-processor RAM and ROM chips 82A and 82B, respectively. Inaddition, microcomputer circuit 33 includes a separate RAM/ROM chip 82Cto provide additional memory capacity. Microprocessor 80 normallyoperates in a reduced power consumption mode and is interrupt driven.Microprocessor 80 is awakened in response to defined interrupt events,which may include A-TRIG, RV-TRIG, LV-TRIG signals generated by timersin digital timer/controller circuit 43 and A-EVENT, RV-EVENT, andLV-EVENT signals generated by sense amplifiers circuit 55, among others.The specific values of the intervals and delays timed out by digitalcontroller/timer circuit 43 are controlled by the microcomputer circuit33 by way of data and control bus from programmed-in parameter valuesand operating modes. In addition, if programmed to operate as a rateresponsive pacemaker, a timed interrupt, e.g., every cycle or every twoseconds, may be provided in order to allow the microprocessor to analyzethe activity sensor data and update the basic A-A, V-A, or V-V escapeinterval, as applicable. In addition, the microprocessor 80 may alsoserve to define variable, operative A-V delay intervals, V-V delayintervals, and the energy delivered to each ventricle and/or atrium.

In one embodiment, microprocessor 80 is a custom microprocessor adaptedto fetch and execute instructions stored in RAM/ROM unit 82 in aconventional manner. It is contemplated, however, that otherimplementations may be suitable to practice the present disclosure. Forexample, an off-the-shelf, commercially available microprocessor ormicrocontroller, or custom application-specific, hardwired logic, orstate-machine type circuit may perform the functions of microprocessor80.

Digital controller/timer circuit 43 operates under the general controlof the microcomputer 33 to control timing and other functions within thepacing circuit 21 and includes a set of timing and associated logiccircuits of which certain ones pertinent to the present disclosure aredepicted. The depicted timing circuits include URI/LRI timers 83A, V-Vdelay timer 83B, intrinsic interval timers 83C for timing elapsedV-EVENT to V-EVENT intervals or V-EVENT to A-EVENT intervals or the V-Vconduction interval, escape interval timers 83D for timing A-A, V-A,and/or V-V pacing escape intervals, an A-V delay interval timer 83E fortiming the A-LVp delay (or A-RVp delay) from a preceding A-EVENT orA-TRIG, a post-ventricular timer 83F for timing post-ventricular timeperiods, and a date/time clock 83G.

The A-V delay interval timer 83E is loaded with an appropriate delayinterval for one ventricular chamber (e.g., either an A-RVp delay or anA-LVp) to time-out starting from a preceding A-PACE or A-EVENT. Theinterval timer 83E triggers pacing stimulus delivery and can be based onone or more prior cardiac cycles (or from a data set empirically derivedfor a given patient). vThe post-event timer 83F times out thepost-ventricular time period following an RV-EVENT or LV-EVENT or aRV-TRIG or LV-TRIG and post-atrial time periods following an A-EVENT orA-TRIG. The durations of the post-event time periods may also beselected as programmable parameters stored in the microcomputer 33. Thepost-ventricular time periods include the PVARP, a post-atrialventricular blanking period (PAVBP), a ventricular blanking period(VBP), a post-ventricular atrial blanking period (PVARP) and aventricular refractory period (VRP) although other periods can besuitably defined depending, at least in part, on the operative circuitryemployed in the pacing engine. The post-atrial time periods include anatrial refractory period (ARP) during which an A-EVENT is ignored forthe purpose of resetting any A-V delay, and an atrial blanking period(ABP) during which atrial sensing is disabled. It should be noted thatthe starting of the post-atrial time periods and the A-V delays can becommenced substantially simultaneously with the start or end of eachA-EVENT or A-TRIG or, in the latter case, upon the end of the A-PACEwhich may follow the A-TRIG. Similarly, the starting of thepost-ventricular time periods and the V-A escape interval can becommenced substantially simultaneously with the start or end of theV-EVENT or V-TRIG or, in the latter case, upon the end of the V-PACEwhich may follow the V-TRIG. The microprocessor 80 also optionallycalculates A-V delays, V-V delays, post-ventricular time periods, andpost-atrial time periods that vary with the sensor-based escape intervalestablished in response to the RCP(s) and/or with the intrinsic atrialand/or ventricular rate.

The output amplifiers circuit 51 contains a RA pace pulse generator (anda LA pace pulse generator if LA pacing is provided), a RV pace pulsegenerator, a LV pace pulse generator, and/or any other pulse generatorconfigured to provide atrial and ventricular pacing. In order to triggergeneration of an RV-PACE or LV-PACE pulse, digital controller/timercircuit 43 generates the RV-TRIG signal at the time-out of the A-RVpdelay (in the case of RV pre-excitation) or the LV-TRIG at the time-outof the A-LVp delay (in the case of LV pre-excitation) provided by A-Vdelay interval timer 83E (or the V-V delay timer 83B). Similarly,digital controller/timer circuit 43 generates an RA-TRIG signal thattriggers output of an RA-PACE pulse (or an LA-TRIG signal that triggersoutput of an LA-PACE pulse, if provided) at the end of the V-A escapeinterval timed by escape interval timers 83D.

The output amplifiers circuit 51 includes switching circuits forcoupling selected pace electrode pairs from among the lead conductorsand the IND-CAN electrode 20 to the RA pace pulse generator (and LA pacepulse generator if provided), RV pace pulse generator and LV pace pulsegenerator. Pace/sense electrode pair selection and control circuit 53selects lead conductors and associated pace electrode pairs to becoupled with the atrial and ventricular output amplifiers within outputamplifiers circuit 51 for accomplishing RA, LA, RV and LV pacing.[000116] The sense amplifiers circuit 55 contains sense amplifiers foratrial and ventricular pacing and sensing. High impedance P-wave andR-wave sense amplifiers may be used to amplify a voltage differencesignal that is generated across the sense electrode pairs by the passageof cardiac depolarization wavefronts. The high impedance senseamplifiers use high gain to amplify the low amplitude signals and relyon pass band filters, time domain filtering and amplitude thresholdcomparison to discriminate a P-wave or R-wave from background electricalnoise. Digital controller/timer circuit 43 controls sensitivity settingsof the atrial and ventricular sense amplifiers 55.

The sense amplifiers may be uncoupled from the sense electrodes duringthe blanking periods before, during, and after delivery of a pace pulseto any of the pace electrodes of the pacing system to avoid saturationof the sense amplifiers. The sense amplifiers circuit 55 includesblanking circuits for uncoupling the selected pairs of the leadconductors and the IND-CAN electrode 20 from the inputs of the RA senseamplifier (and LA sense amplifier if provided), RV sense amplifier andLV sense amplifier during the ABP, PVABP and VBP. The sense amplifierscircuit 55 also includes switching circuits for coupling selected senseelectrode lead conductors and the IND-CAN electrode 20 to the RA senseamplifier (and LA sense amplifier if provided), RV sense amplifier andLV sense amplifier. Again, sense electrode selection and control circuit53 selects conductors and associated sense electrode pairs to be coupledwith the atrial and ventricular sense amplifiers within the outputamplifiers circuit 51 and sense amplifiers circuit 55 for accomplishingRA, LA, RV, and LV sensing along desired unipolar and bipolar sensingvectors.

Right atrial depolarizations or P-waves in the RA-SENSE signal that aresensed by the RA sense amplifier result in a RA-EVENT signal that iscommunicated to the digital controller/timer circuit 43. Similarly, leftatrial depolarizations or P-waves in the LA-SENSE signal that are sensedby the LA sense amplifier, if provided, result in a LA-EVENT signal thatis communicated to the digital controller/timer circuit 43. Ventriculardepolarizations or R-waves in the RV-SENSE signal are sensed by aventricular sense amplifier result in an RV-EVENT signal that iscommunicated to the digital controller/timer circuit 43. Similarly,ventricular depolarizations or R-waves in the LV-SENSE signal are sensedby a ventricular sense amplifier result in an LV-EVENT signal that iscommunicated to the digital controller/timer circuit 43. The RV-EVENT,LV-EVENT, and RA-EVENT, LA-SENSE signals may be refractory ornon-refractory and can inadvertently be triggered by electrical noisesignals or aberrantly conducted depolarization waves rather than trueR-waves or P-waves.

The techniques described in this disclosure, including those attributedto the IMD 16, the computing apparatus 140, and/or various constituentcomponents, may be implemented, at least in part, in hardware, software,firmware, or any combination thereof. For example, various aspects ofthe techniques may be implemented within one or more processors,including one or more microprocessors, DSPs, ASICs, FPGAs, or any otherequivalent integrated or discrete logic circuitry, as well as anycombinations of such components, embodied in programmers, such asphysician or patient programmers, stimulators, image processing devices,or other devices. The term “module,” “processor,” or “processingcircuitry” may generally refer to any of the foregoing logic circuitry,alone or in combination with other logic circuitry, or any otherequivalent circuitry.

Such hardware, software, and/or firmware may be implemented within thesame device or within separate devices to support the various operationsand functions described in this disclosure. In addition, any of thedescribed units, modules, or components may be implemented together orseparately as discrete but interoperable logic devices. Depiction ofdifferent features as modules or units is intended to highlightdifferent functional aspects and does not necessarily imply that suchmodules or units must be realized by separate hardware or softwarecomponents. Rather, functionality associated with one or more modules orunits may be performed by separate hardware or software components orintegrated within common or separate hardware or software components.

When implemented in software, the functionality ascribed to the systems,devices and techniques described in this disclosure may be embodied asinstructions on a computer-readable medium such as RAM, ROM, NVRAM,EEPROM, FLASH memory, magnetic data storage media, optical data storagemedia, or the like. The instructions may be executed by processingcircuitry and/or one or more processors to support one or more aspectsof the functionality described in this disclosure.

ILLUSTRATIVE EMBODIMENTS

Embodiment 1. A system for use in cardiac evaluation comprising:

-   -   an electrode apparatus comprising a portable amplifier and a        plurality of external electrodes to be disposed proximate a        patient's skin;    -   a portable computing apparatus comprising processing circuitry,        the computing apparatus operably coupled to the electrode        apparatus and configured to be operably coupled to an        implantable pacing device of the patient, the portable computing        apparatus configured to:    -   monitor electrical activity from tissue of a patient using the        plurality of external electrodes to generate a plurality of        electrical signals over time;    -   perform at least one of:    -   optimizing at least one pacing parameter of the implantable        pacing device based on the plurality of electrical signals; and    -   determining cardiac synchrony based on the plurality of        electrical signals.

Embodiment 2. The system of embodiment 1, wherein the at least onepacing parameter comprises one or more of pacing rate, atrial pacingrate, ventricular pacing rate, A-V interval, V-V interval, pacing pulsewidth, pacing vector, multipoint pacing timings, and pacing voltage.

Embodiment 3. The system as in any one of embodiments 1-2, whereinoptimizing the at least one pacing parameter of the implantable devicecomprises:

-   -   scanning different values of the at least one pacing parameter;        and    -   selecting at least one of the scanned values of the at least one        pacing parameter that provides the highest electrical synchrony.

Embodiment 4. The system as in any one of embodiments 1-3, whereindetermining cardiac synchrony comprises automatically determining one ormore pacing device metrics.

Embodiment 5. The system of embodiment 4, wherein the pacing devicemetrics comprise one or more of pacing thresholds and lead impedances.

Embodiment 6. The system of embodiment 4, wherein the portable computingdevice is further configured to transmit the one or more pacing devicemetrics to a display device.

Embodiment 7. The system of embodiment 6, wherein the display devicecomprises one or more of a smart phone, a tablet, and a smart watch.

Embodiment 8. The system as in any one of embodiments 1-7, wherein theportable computing device comprises a portable smart amplifier.

Embodiment 9. The system as in any one of embodiments 1-8, wherein theportable computing apparatus is configured to perform the cardiacsynchrony assessment automatically when predetermined conditions aremet.

Embodiment 10. The system of embodiment 9, wherein the predefinedconditions comprise one or more of a time, a time interval, and a heartrate of the patient.

Embodiment 11. A method for use in cardiac evaluation, comprising:

-   -   monitoring electrical activity from tissue of a patient using a        plurality of external electrodes to generate a plurality of        electrical signals over time; and    -   using a portable computing apparatus operably coupled to the        plurality of electrodes, performing at least one of:    -   optimizing at least one pacing parameter of the implantable        pacing device based on the plurality of electrical signals; and    -   determining cardiac synchrony based on the plurality of        electrical signals.

Embodiment 12. The method of embodiment 11, wherein the at least onepacing parameter comprises one or more of pacing rate, atrial pacingrate, ventricular pacing rate, A-V interval, V-V interval, pacing pulsewidth, pacing vector, multipoint pacing timings, and pacing voltage.

Embodiment 13. The method as in any one of embodiments 11-12, whereinoptimizing the at least one pacing parameter of the implantable devicecomprises:

-   -   scanning different values of the at least one pacing parameter;        and    -   selecting at least one of the scanned values of the at least one        pacing parameter that provides the highest electrical synchrony.

Embodiment 14. The method as in any one of embodiments 11-13, whereinthe cardiac synchrony assessment comprises automatically determining oneor more pacing device metrics.

Embodiment 15. A system for use in cardiac evaluation comprising:

-   -   an electrode apparatus comprising a portable amplifier and a        plurality of external electrodes to be disposed proximate a        patient's skin;    -   a portable computing apparatus comprising processing circuitry,        the computing apparatus operably coupled to the electrode        apparatus and configured to be operably coupled to an        implantable pacing device of the patient, the portable computing        apparatus configured to:        -   monitor electrical activity from tissue of a patient using            the plurality of external electrodes to generate a plurality            of electrical signals over time;        -   measure one or more parameters of the patient based on the            plurality of electrical signals;        -   determine one or more metrics of the patient based on the            one or more parameters; and        -   transmit the one or more metrics to a smart device.

Embodiment 16. The system of embodiment 15, wherein determining the oneor more metrics of the patient based on the one or more parameterscomprises determining whether the one or more parameters is greater thana predetermined threshold.

Embodiment 17. The system of embodiment 16, wherein the portablecomputing apparatus is configured to transmit an alert to the smartdevice based on a determination that the one or more parameters isgreater than the predetermined threshold.

Embodiment 18. The system as in any one of embodiments 15-17 wherein theone or more metrics comprise one or more indicators of cardiacdyssynchrony.

Embodiment 19. The system as in any one of embodiments 15-18, whereinthe one or more metrics comprise one or more indicators of a risk ofarrhythmias.

Embodiment 20. The system as in any one of embodiments 15-19, whereinthe one or more metrics comprise one or more of a standard deviation ofactivation times (SDAT) metric, an average of left ventricularactivation times (LVAT) metric, a standard deviation of left ventricularactivation times metric, a standard deviation of right ventricularactivation times metric, a QT dispersion metric, an activation recoveryinterval metric, and a recovery time metric.

Embodiment 21. A method for use in cardiac evaluation, comprising:

-   -   monitoring electrical activity from tissue of a patient using a        plurality of external electrodes to generate a plurality of        electrical signals over time; and    -   using a portable computing apparatus operably coupled to the        plurality of electrodes:        -   measuring one or more parameters of the patient based on the            plurality of electrical signals;        -   determining one or more metrics of the patient based on the            one or more parameters; and        -   transmitting the one or more metrics to a smart device.

What is claimed:
 1. A system for use in cardiac evaluation comprising:an electrode apparatus comprising a portable amplifier and a pluralityof external electrodes to be disposed proximate a patient's skin; aportable computing apparatus comprising processing circuitry, thecomputing apparatus operably coupled to the electrode apparatus andconfigured to be operably coupled to an implantable pacing device of thepatient, the portable computing apparatus configured to: monitorelectrical activity from tissue of a patient using the plurality ofexternal electrodes to generate a plurality of electrical signals overtime; perform at least one of: optimizing at least one pacing parameterof the implantable pacing device based on the plurality of electricalsignals; and determining cardiac synchrony based on the plurality ofelectrical signals.
 2. The system of claim 1, wherein the at least onepacing parameter comprises one or more of pacing rate, atrial pacingrate, ventricular pacing rate, A-V interval, V-V interval, pacing pulsewidth, pacing vector, multipoint pacing timings, and pacing voltage. 3.The system of claim 1, wherein optimizing the at least one pacingparameter of the implantable device comprises: scanning different valuesof the at least one pacing parameter; and selecting at least one of thescanned values of the at least one pacing parameter that provides thehighest electrical synchrony.
 4. The system of claim 1, whereindetermining cardiac synchrony comprises automatically determining one ormore pacing device metrics.
 5. The system of claim 4, wherein the pacingdevice metrics comprise one or more of pacing thresholds and leadimpedances.
 6. The system of claim 4, wherein the portable computingdevice is further configured to transmit the one or more pacing devicemetrics to a display device.
 7. The system of claim 6, wherein thedisplay device comprises one or more of a smart phone, a tablet, and asmart watch.
 8. The system of claim 1, wherein the portable computingdevice comprises a portable smart amplifier.
 9. The system of claim 1,wherein the portable computing apparatus is configured to perform thecardiac synchrony assessment automatically when predetermined conditionsare met.
 10. The system of claim 9, wherein the predefined conditionscomprise one or more of a time, a time interval, and a heart rate of thepatient.
 11. The electrode apparatus of claim 1, wherein the pluralityof external electrodes are disposed on a C-shaped belt configured towrap around a left side of a torso from a sternum on a front side to aspine on a back side.
 12. A method for use in cardiac evaluation,comprising: monitoring electrical activity from tissue of a patientusing a plurality of external electrodes to generate a plurality ofelectrical signals over time; and using a portable computing apparatusoperably coupled to the plurality of electrodes, performing at least oneof: optimizing at least one pacing parameter of the implantable pacingdevice based on the plurality of electrical signals; and determiningcardiac synchrony based on the plurality of electrical signals.
 13. Themethod of claim 12, wherein the at least one pacing parameter comprisesone or more of pacing rate, atrial pacing rate, ventricular pacing rate,A-V interval, V-V interval, pacing pulse width, pacing vector,multipoint pacing timings, and pacing voltage.
 14. The method of claim12, wherein optimizing the at least one pacing parameter of theimplantable device comprises: scanning different values of the at leastone pacing parameter; and selecting at least one of the scanned valuesof the at least one pacing parameter that provides the highestelectrical synchrony.
 15. The method of claim 12, wherein the cardiacsynchrony assessment comprises automatically determining one or morepacing device metrics.
 16. A system for use in cardiac evaluationcomprising: an electrode apparatus comprising a portable amplifier and aplurality of external electrodes to be disposed proximate to a patient'sskin; a portable computing apparatus comprising processing circuitry,the computing apparatus operably coupled to the electrode apparatus andconfigured to be operably coupled to an implantable pacing device of thepatient, the portable computing apparatus configured to: monitorelectrical activity from tissue of a patient using the plurality ofexternal electrodes to generate a plurality of electrical signals overtime; measure one or more parameters of the patient based on theplurality of electrical signals; determine one or more metrics of thepatient based on the one or more parameters; and transmit the one ormore metrics to a smart device.
 17. The system of claim 16, whereindetermining the one or more metrics of the patient based on the one ormore parameters comprises determining whether the one or more parametersis greater than a predetermined threshold.
 18. The system of claim 17,wherein the portable computing apparatus is configured to transmit analert to the smart device based on a determination that the one or moreparameters is greater than the predetermined threshold.
 19. The systemof claim 16, wherein the one or more metrics comprise one or moreindicators of cardiac dyssynchrony.
 20. The system of claim 16 whereinthe one or more metrics comprise one or more indicators of a risk ofarrhythmias.
 21. The system of claim 16, wherein the one or more metricscomprise one or more of a standard deviation of activation times (SDAT)metric, an average of left ventricular activation times (LVAT) metric, astandard deviation of left ventricular activation times metric, astandard deviation of right ventricular activation times metric, a QTdispersion metric, an activation recovery interval metric, and arecovery time metric.
 22. A method for use in cardiac evaluation,comprising: monitoring electrical activity from tissue of a patientusing a plurality of external electrodes to generate a plurality ofelectrical signals over time; and using a portable computing apparatusoperably coupled to the plurality of electrodes: measuring one or moreparameters of the patient based on the plurality of electrical signals;determining one or more metrics of the patient based on the one or moreparameters; and transmitting the one or more metrics to a smart device.